Thanks for all the info.
Let me explain what happens with use first.
When you select A4WD the front axle is locked in and stays locked in all the time. The front driveshaft tis spinning, but the transfer case electromagnetic clutch is not locked in. You will get poor fuel mileage in this selection as well as some minor power loss due to more components turning.
In 2H the front axle is not engaged nor is the driveshaft or transfer case. The best option for fuel mileage.
In 4high you have the front axle locked in and the driveshaft and the transfer case. This should only be used in mud, snow, ice or poor traction surfaces.
What you need to do is shift from 4high to 2high then have an assistant lay beside the vehicle and you pull forward a foot to see if the front driveshaft turns. If it does then the transfer case or front axle is locked in. If the driveshaft does not turn then everything is unlocked.
If the driveshaft did turn then you need to get the vehicle on a rack and duplicate this. if the driveshaft still turns then the transfer case has an issue. If the driveshaft does not turn then turn both front wheels in the same direction. if the driveshaft turns then your front axle actuator has a concern.
Some vehicles do have a slight whine noise in 4wd use that comes from the transfer case or front axle, I would get a tech to listen to it and see if it is abnormal meaning you have a bearing failure in the front axle or transfer case that needs to be listened to from underneath.
Sometimes shifting from 4 high to 2 high then backing up and turning in both directions to help release driveline tension will assist in releasing everything.
If the front driveshaft is not turning in 2 high and you still getting a binding sensation then your rear axle limited slip clutches are faulty and grabbing to much, binding and needing replacement.
Let me know if this helps out.